What is Polymer Clay?

Polymer clay is polyvinyl chloride or PVC similar to the plastic used in plumbing today.  When it is baked properly, polymer clay chemically changes to form a solid mass that doesn't shrink.  You can heat it again, which will soften it slightly without melting.  A word of caution...if you heat it too hot, it will darken and can give off noxious fumes and possibly catch fire. Use an oven thermometer to check your oven's temperature.

Is it Clay?:  Polymer clay is not a true clay.  It is called clay because of it's moldable properties, not because it is traditional clay.  The word Polymer is added to differentiate.  Polymer clay can be molded  to imitate a variety of materials making it very versatile.

In it's simplest definition, true clay is finely ground sand particles mixed with water¹ and heated to melt the particles.  It needs to be heated much hotter than a household oven or toaster oven can heat.

Polymer means many units of a molecule, in this case vinyl chloride, strung together.²  Basically polymer clay is tiny grains of plastic or polyvinyl chlorides (PVC) with plasticizers and colorants mixed in.  The plasticizers is the greasy spot left on a piece of paper after you leave clay sitting on it.

After you mold your polymer clay, you put it in your oven and heat it to the temperature on your package.  The temperature is based on the type of plasticizer used in that particular brand of clay.  While heating, the grains of plastic are growing and sticking together.  As the piece gets hotter, the fused piece hardens permanently.

Reason for not using a finished piece to serve food on:  When heated, because the piece is porous, there may be some residual plasticizer left in the clay that acidic foods or liquids would release.  The plasticizer is unhealthy to ingest.

Endnotes

1 Roche, Nan. The New Clay. (Rockville, MD: Flower Valley Press, 1991), 7.
2 Roche, Nan. The New Clay. (Rockville, MD: Flower Valley Press, 1991), 127.